Dr. Ahmad Redaa
2026-01-28
Source: https://www.geosociety.org/
Source: https://www.geosociety.org/
Plate tectonics explains the movement of rigid lithospheric plates and the geological processes at their boundaries.
Lithosphere
Rigid outer shell of the Earth (crust + uppermost mantle)
Asthenosphere
Hot, weak upper mantle beneath the lithosphere that allows plate
motion
Plate
Large, rigid slab of lithosphere moving over the asthenosphere
Divergent boundary
Plates move apart; new crust forms
Example: Red Sea rift
Convergent boundary
Plates move toward each other
Transform boundary
Plates slide past one another
Example: Dead Sea Transform
Trench
Deep-sea feature marking the surface expression of subduction
Forearc
Region between the trench and the volcanic
arc
Volcanic arc
Chain of volcanoes and plutons formed above a subducting slab
Backarc
Region behind the volcanic arc, away from the
trench
Subduction
Sinking of dense oceanic lithosphere into the mantle
Arc magmatism
Volcanism and plutonism above subduction zones
Orogeny
Mountain building through collision and crustal thickening
Rifting
Stretching and thinning of continental lithosphere
Craton
Stable continental core
Shield
Exposed Precambrian basement of a craton
Terrane
Fault-bounded crustal block with a distinct geologic history
Suture zone
Remnant of a closed ocean between colliding plates
Ophiolite
Fragment of oceanic lithosphere emplaced onto continental crust
Location map of the Arabian Shield, Source: Kashghari et al. (2025)
Image generated by NotebookLM
General cycle: 1. Continental breakup and
rifting
2. Ocean basin formation
3. Subduction and arc magmatism
4. Continental collision and assembly
5. Erosion and stabilization → renewed breakup